All, GHC 6.8 has a lot of new names for language extensions which are not yet listed in Language.Haskell.Extension: UnicodeSyntax PatternSignatures UnliftedFFITypes LiberalTypeSynonyms TypeOperators PArr RecordWildCards RecordPuns DisambiguateRecordFields OverloadedStrings GADTs MonoPatBinds RelaxedPolyRec ExtendedDefaultRules UnboxedTuples DeriveDataTypeable ConstrainedClassMethods These are the extension names you can list in the "extensions:" field in a .cabal file and are also in the {-# LANGUAGE #-} pragma. So I propose we add all of these to the Extension enumeration data type. I'd like to keep this addition separate from the proposal to make Extension a String or newtype String, since I expect even in that case we need a central list of extensions so different implementations can agree on names when they implement the same extensions, or to ensure they pick different names for different extensions. It'd also be nice if we could document all these extensions in the Language.Haskell.Extension module so we can refer to it from the cabal documentation about the extensions field. Duncan